Intel showed off a pocket-sized device that monitors power usage by gadgets and appliances across a house, from toasters to computer monitors and video game consoles.

The small black box plugged into a single power outlet and wirelessly sent its data to a partner display device, which had an Intel Atom processor and the MeeGo operating system. A sensor in the box could detect which appliances were being turned on or off by watching for their unique electricity usage patterns. That allows the creation of logs that can show, for instance, at what hours each day an Xbox or certain lights have been turned on.

The setup aims to help users cut back energy usage. The display device, for instance, showed a clock with yellow and red tick marks to indicate when electricity prices peak during a day, so a user can avoid tasks such as washing laundry at those times.

A user could also activate custom settings on the touch screen of the display device, which was about the size of a tall book, to modify the thermostat temperature or to turn off some appliances, Intel said in a statement.

Users also may be able to download applications for the device from Intel's AppUp Store, which the company created as a market for apps on Atom devices.

Intel is working on a reference design for the sensor prototype, said Justin Rattner, the head of Intel Labs, after an onstage demonstration of the technology on Wednesday at the Intel Developer Forum in Beijing.

Mary Murphy-Hoye, an Intel engineer who had a similar sensor system set up in her home, told stories during the demo about its usefulness. First, by monitoring her laundry machine's energy use, she found the cold water setting still drew energy because the machine would still partly heat the water, she said. She switched a setting on the machine to prevent that heating and save more energy.

"You can reduce your energy consumption by 15 to 30 percent," she said.

Second, logs that showed the use of each electrical device in the house allowed Murphy-Hoye to see when her son was playing Xbox each day, sometimes at times he was not allowed to, she said.

"No longer can he tell me ... what he wants me to think he did," she said. "Mom's watching."

Rattner "intentionally" did not discuss automated home control systems, but with certain additions a system could automatically do things like turn off a light that is not being used, he said.

Separately, Intel researchers are also looking at other power projects including new ways for households to store energy, Rattner said. For instance, power being stored in electric cars could be fed back into the power grid, he said. Another topic is ways for homes that generate their own power, such as with wind turbines, to store that energy if it goes unused, rather than selling it back to the grid, he said.

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